The invention relates to the field of oral ortheses intended, in particular, to treat snoring and the increase in the resistances of the upper airways during sleep.
As is known, snoring is the consequence of a muscular hypotonia which occurs during sleeping. This is because, when the muscles of the jaw are relaxed, the mandible has a natural tendency to move backwards, carrying the tongue towards the rear of the oral cavity as it moves. The oral respiratory tract thus decreases in size and causes turbulence in the respiratory flow, which is responsible for the vibrations of the soft palate and the adjacent soft tissue. This vibration causes the well-known audible phenomenon of snoring.
In some cases, in particular when the dimensions of the tongue are large, this obstruction may be complete, leading therefore to interruptions in the respiration, or apnoeas. These phenomena impair the quality of sleep and the neuro-vegetative reflexes responsible for arterial, systemic and pulmonary hypertension. Repetition of these apnoeas results for the patient in fatigue on waking and diurnal somnolence. It can thus be seen that this is a true pathology.
In some cases, recourse is made to placing patients, when they sleep, under spontaneous ventilation with continuous positive pressure using a nasal mask. Although effective, this solution nevertheless has the main drawback of needing specific equipment which constitutes a significant restraint.
Another solution which has been proposed for combating these phenomena of apnoeas during sleep consists in performing a resection operation of the soft palate. Besides the fact that this solution constitutes a painful operation, it is not always effective. It also leads to changes in the intrabuccal morphology, which may interfere with swallowing.
Complex instruments, allowing the lower jaw to be advanced by propelling the mandible, have also been proposed for combatting the snoring. However, these systems are integral and operate by fully immobilizing the mandible in an advanced position.
From U.S. Pat. No. 5,365,945, incorporated herein by reference, is known to disclose an intrabuccal device that comprises two shells made of thermoformed plastic material. The first of these shells covers the superior arch of the oral cavity. The second of these shells covers the inferior arch. This device comprises means that act at the said shells and that generate on the mandible a propulsive force oriented in the direction of the mandibular propulsion and in the posteroanterior sense. Moreover, these means allow the shell covering the inferior arch of the mandible to move with a limited degree regard to the shell covering the superior arch of the maxilla.
It has been observed that the mandible moves in the posteroanterior sense at each swallowing and this occurs about two hundred times per night. This movement is impossible with the proposed immobilization systems and with the proposed device, which causes a discomfort in such fitted patients and may cause algo-dysfunctional syndromes of the temporomandibular articulation.
The object of the invention is to provide an instrument which permits to keep the mandible in propulsive position, while allowing it to move in relation to the upper maxilla.
The invention relates to an intrabuccal device comprising two shells made of thermoformed plastic material, the first of which respectively covers the superior arch and the second of which covers the inferior arch of a patient""s oral cavity, and provided with means that act at the said shells and can generate a mandibular propulsive force oriented in the direction of the mandibular propulsion and in the posteroanterior sense.
The device is characterized in that it allows mandibular retro-propulsion.
In other words, the invention consists in providing the said shells with mechanical means which, in the absence of any other constraint, in particular a physiological one, induce the mandible to move in the forward direction relative to the maxilla.
According to a first embodiment of the invention, these means comprise:
on one of the two shells, above the premolars, a ring that projects beyond the occlusal plane,
and on the other shell, a pair of free arms that project beyond the occlusal plane and are parallel to it, these two arms being fastened on the anterior lingual face of the shell and being oriented in the general direction of the occlusion line, these arms being intended to engage and slide in the said rings so as to keep a shift of the mandible to the front of the maxilla, while allowing lateral movements.
In other words, the mandible is held in a propelling position relative to the upper jaw by the interaction of the rings and the arms that are respectively secured to the upper and lower jaw. Moreover, the degree of freedom corresponding to the possibility of the arms sliding inside the rings allows the two maxillae a certain capacity to move.
By interacting with the rings, the arms make it possible to keep a forward shift of the mandible relative to the maxilla while allowing lateral movements, swallowing and breathing through the mouth. In addition, this allows mandibular retrusion in occlusion for convenience, in particular during swallowing. Finally, this system reduces the risks of disorders of the temporomandibular articulation.
To solve the problem of engagement and, above all, that of untimely decoupling, the free ends of the arms are curved towards the vestibular space.
In other words, the two shells constitute independent units which are put together by passing the arms through the rings. Because the ends of the arms are curved, the arms need to be deformed slightly to make them enter the rings, which prevents any untimely decoupling within the patient""s mouth.
In view of the great complexity of the kinematics of the temporomandibular articulation, it has been observed that a greater freedom of movement is obtained when each of the rings has an elliptical shape and is placed substantially between the first and second premolars.
In the same way, the capacity for movement is increased when each ring is orthogonal to the occlusion line, and therefore to the direction of the arms.
As already seen, keeping the propulsion is obtained thanks to the spring effect of the free arm/s. This is why in order to increase the elasticity effect further, while improving the strength of the assembly, the arms form the branches of a single V-shaped piece that are directed towards the rear of the mouth and the free ends of which are placed substantially above the first molar.
As is conventional in the field of orthodontics, the rings and the free arms are made of stainless steel.
According to another embodiment of the invention, the two shells receive hooks, intended in turn to receive elastic elements tending to propel the mandible forward. More precisely, the hooks of the lower shell are fastened adjacent to its ends, and advantageously, with the second premolar, whereas the hooks of the upper shell are fastened advantageously above each of the junction regions between the central and lateral incisors.
According to another embodiment of the invention, the generated propulsive force is of magnetic source, permanent magnets being incorporated at the shells in order to generate repulsive forces.
To solve the problem of individualized fitting of this instrument each shell has a top side made of a semirigid thermoformable material, and a bottom side made of a more flexible thermoformable material. In this way, each patient can fit the shell to his own imprint simply by heating, in particular in boiling water, then fitting it over each of his arches.
As can be seen, the invention consists in causing the mandible to propel in order to prevent the tongue from sliding backwards. The advantages of the invention are improved further when, at its two posterior ends, the upper shell has two lobes extending backwards and intended to serve as a support for the lateral portion of the soft palate. In this way, the upper shell has a tendency to move and push the soft palate away in order to prevent it from coming into contact with the tongue.
In complementary fashion, the efficiency of the device is improved if the lower shell has brackets placed in proximity to the free ends of the shell and oriented inwards in the direction of one another, these brackets being intended to bear on the lateral parts of the tongue in order to prevent it from rising. In other words, this avoids the rising of the tongue which is inherent in muscular hypotonia. Of course, these arrangements are particularly advantageous in the case of a patient suffering from macroglossia.